1. Field of the Invention
The present invention relates to a magnetic recording and reproducing device for recording data on a magnetic tape having an anisotropic property by a helical recording system.
2. Description of the Related Art
In a magnetic recording and reproducing device using a magnetic tape, in order to achieve a high density recording operation, a helical recording system is employed that data is obliquely recorded with respect to the longitudinal direction of the tape by a magnetic head attached to a rotary drum.
In this helical recording system, a guard band between adjacent tracks is eliminated to enhance a recording track density. However, a cross-talk that the head picks up a signal on the adjacent track upon reproducing data is undesirably generated.
Thus, to cancel the deterioration of reproduction due to the cross-talk, an azimuth recording system is employed. In the azimuth recording system, data is recorded by using a rotary head (a double azimuth head) having two magnetic heads attached whose azimuth angles (angles of magnetic gaps) have opposite symbols to each other such as +5 to 20° and −5 to 20° (as for the symbols of the angles, a counterclockwise case relative to a reference line is referred to as + and a clockwise case is referred to as −, hereinafter) so that the two heads alternately scan the tape and the azimuth angles of adjacent tracks are different from each other.
As an example of a magnetic recording medium related to the present invention, a magnetic recording medium disclosed in Japanese Patent Application Laid-Open No. hei 5-36061 is proposed.
In the above-described azimuth recording system, the cross-talk of the adjacent tracks can be reduced. However, in an obliquely evaporated tape, an optimum point peak of an electromagnetic conversion property is present in the moving direction of the tape. An azimuth is set so that a great transfer loss is undesirably generated in an electromagnetic conversion in one magnetic head. Accordingly, for instance, as shown in FIG. 4, RF outputs of the two magnetic heads are unbalanced. Thus, the efficiency of the RF output is not good as the magnetic recording and reproducing system.
A magnetic recording and reproducing system which has been usually used has not good efficiency under its recording density, but meets only the improvement of the performance of a media head. However, a magnetic recording and reproducing device in which the recording density is improved, a track pitch is not larger than 5 μm and the shortest recording wavelength is not larger than 0.3 μm cannot undesirably cover the deterioration of the efficiency only by the countermeasure of a head whose recording and reproducing efficiency is improved by using a thin film type head for any of recording and reproducing heads and media whose property meets the thin film type head.
FIG. 4A shows a relation between an angle θ formed by the azimuth of a head and the longitudinal direction of a tape (the direction of an optimum point peak of an electromagnetic conversion property) and an RF output. FIG. 4B shows azimuth angles of magnetic heads (1ch head, 2ch head) on a first channel and a second channel in a magnetic tape. FIG. 4C shows the definition of the angles θ1 and θ2 in FIG. 4A, and FIG. 4D shows the definition of the angle θ in FIG. 4A.
In FIG. 4, assuming that the azimuth of the head (an inclination angle relative to a reference line shown by a broken line in the drawing (here, a cross line intersecting perpendicularly to the moving direction of the head) is 25° and an angle formed by the longitudinal direction of the tape and the moving direction of the head is 15°, an angle θ1 formed by the azimuth direction of the magnetic head (1ch head) of the first channel and the longitudinal direction of the tape is 10° and the angle θ2 formed by the azimuth direction of the magnetic head (2ch head) of the second channel and the longitudinal direction of the tape is 140°.
Therefore, there is a large level difference between the RF outputs of the 1ch head and the 2ch head, which has a great unbalance.